Analysis of the effects of noradrenaline and tyramine in isolated middle cerebral and femoral arteries of cat.
1. Tyramine and noradrenaline (NA) caused dose-dependent contractions in middle cerebral and femoral arteries of cat, which were decreased by phentolamine. 2. Gangliectomy increased the contraction evoked by NA in brain arteries. 3. Reserpine pretreatment and/or gangliectomy reduced the contraction caused by tyramine, the maximal responses being unmodified in the cerebral vessels. 4. Tyramine induced Ca2+-dependent tritium release from brain and femoral arteries, which was reduced by reserpine pretreatment and/or gangliectomy. 5. These data suggest that tyramine has a direct component, apart from an indirect one, in brain arteries. The mechanisms by which NA induces slight contraction in them, including the role of Ca2+, are postulated.
D000818:Animals; D002118:Calcium / Q000502:physiology; D002415:Cats; D002536:Cerebral Arteries / Q000187:drug effects / Q000378:metabolism; D004533:Egtazic Acid / Q000494:pharmacology; D005260:Female; D005263:Femoral Artery / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000378:metabolism / Q000494:pharmacology*; D009928:Organ Specificity; D010646:Phentolamine / Q000494:pharmacology; D014439:Tyramine / Q000494:pharmacology*; D014661:Vasoconstriction / Q000187:drug effects*
D004533:Egtazic Acid; D002118:Calcium; D009638:Norepinephrine; D014439:Tyramine; D010646:Phentolamine